1. Field of the Invention
The present invention is directed to a thrust plate assembly, and more particularly to a thrust plate assembly for a motor vehicle friction clutch with automatic wear compensation.
2. Discussion of the Prior Art
Thrust plate subassemblies for motor vehicle friction clutches with automatic wear compensation are generally constructed so that a pressure plate is pressed by a diaphragm spring in the direction of a flywheel and, accordingly, friction facings of a clutch disk are clamped between the pressure plate and the flywheel. The diaphragm spring is supported at the pressure plate by a wear adjustment device in the form of two adjustment rings which are rotatable with respect to one another and pretensioned in one wear adjustment direction. A play sensor is provided which has a shift portion that penetrates a through-opening in the pressure plate and makes contact with the flywheel when wear occurs. A lever portion is connected with the shaft portion and contacts one of the adjustment rings, so that an adjustment of the wear adjustment device is prevented in the disengaged state when no wear exists. When wear occurs and the shaft portion thus makes contact with the flywheel, the contacting force of the lever portion at the corresponding adjustment ring is reduced by an amount corresponding to the amount of wear. During the subsequent clutch release process, the wear adjustment device can compensate for this force difference by relative rotation of the two adjustment rings until the adjustment rings are again locked.
The play sensor is tilted in the respective through-opening of the pressure plate by, among others, a helical pressure spring, so that the shaft portion is held in the through-opening by a press fit or frictional clamping fit. The frictional clamping fit is temporarily canceled during the wear detection process described above, so that the shaft can be displaced in the through-opening of the pressure plate.
However, securing the play sensor to the pressure plate by means of the frictional clamping fit often leads to the problem of a relatively imprecisely definable fixing force. Thus, vibrations or shaking excitations can also lead to a temporary cancellation of the frictional clamping fit and therefore to the risk that the play sensor will be displaced in an unwanted manner.